What is this U.V. artifact?
It's hard to say exactly what the items are that are perplexing you. One possibility is that they may be one or more faces on the inside of your mesh that you created by accident. If this is the case, you might locate them by switching to wireframe mode. To see if it's a poorly unwrapped face, switch to textured mode in the 3D viewport, and move the point that is active in the UV editor window and see where the texture on the textured mesh moves.